The formula of multiplying two digits by two digits is: the product of ten digits is connected, and the cross product is supplemented by zero. When calculating, if the product of single digits is one digit, then the ten digits are filled with 0, and then written after the product of ten digits; For example, the first stage of 34x82 is 2408, not 248.

A fast calculation method of multiplying two digits by 1 1;

The fast calculation method of multiplying two digits by 1 1 can be summarized as a formula: pull at both ends, add one in the middle, and make ten into one. Take 34× 1 1 as an example, 3+4=7, and then put 7 in the middle of 3 and 4, the result is 374; If we calculate 84× 1 1, 8+4= 12 according to the method of all decimals, the result is 924.

Elementary school 1 to grade 6 mathematics knowledge summary;

The first grade of primary school: 99 multiplication formula, learn basic addition and subtraction multiplication formula: recite 99 multiplication formula well and be familiar with single-digit multiplication formula;

The second grade of primary school: improve the multiplication formula table, strengthen the knowledge of the first grade, and learn the mixed operation of division and basic geometry;

The third grade of primary school: learn multiplication and commutation law, geometric area perimeter, time and unit. Distance calculation, distribution law, fractional decimal;

The fourth grade of primary school: the natural number of line angle is an integer, the prime factor is trapezoidal symmetry, and the fraction is calculated;

The fifth grade of primary school: multiplication and division of fractions and decimals, algebraic equations and average values, comparative size transformation, graphic area and volume;

Sixth grade: proportional percentage probability, circular fan, cylinder and cone.